Stacked conformation radiotherapy system and particle beam therapy apparatus employing the same

Abstract

A stacked conformation radiotherapy system capable of homogenizing a radiation dose distribution, including an irradiation head and irradiation control means. The irradiation head projects a particle beam accelerated by an accelerator, toward an object to-be-irradiated, and it includes wobbler electromagnets for deflecting and scanning the particle beam. In carrying out stacked conformation radiotherapy by deflecting and scanning the particle beam, the irradiation control means subjects the wobbler electromagnets to magnetization controls so that the particle beam may depict a one-stroke revolving orbit which begins with a start point and returns to the start point, and it performs a control so that the irradiation period of the particle beam to be outputted from the irradiation head may become integral times a wobbler cycle which is required for the particle beam to make one revolution of the revolving orbit.

1. A stacked conformation radiotherapy system comprising an accelerator which accelerates a particle beam generated from an ion source, an irradiation head which projects the particle beam accelerated by said accelerator, toward an object to-be-irradiated, and which includes wobbler electromagnets for deflecting and scanning the particle beam, and an irradiation controller for carrying out stacked conformation radiotherapy by controlling the ion source, said accelerator and said irradiation head, said irradiation controller deflecting and scanning the particle beam by subjecting the wobbler electromagnets to magnetization controls;
 wherein said irradiation controller performs the magnetization controls of the wobbler electromagnets so that the particle beam depicts a one-stroke revolving orbit which begins with a start point and returns to the start point, controls an irradiation dose of the stacked conformation radiotherapy in a depth direction of the object to be irradiated by altering a particle beam intensity layer by layer, and sets a total emission period of the particle beam to be outputted from said accelerator, prior to irradiation, such that the total emission period in each layer is an integral multiple of a wobbler cycle which is required for the particle beam to make one revolution of the revolving orbit. 
 
     
     
       2. A stacked conformation radiotherapy system as defined in  claim 1 , wherein said accelerator is an accelerator which emits the particle beam with a pulse width longer than the wobbler cycle, and wherein said irradiation controller alters the number of the particle beams every layer of the stacked conformation radiotherapy, thereby to control an irradiation dose of each layer in a depth direction of the object to-be-irradiated, and it performs a control so that the emission period of each pulse of the particle beam is an integral multiple of the wobbler cycle. 
     
     
       3. A stacked conformation radiotherapy system as defined in  claim 1 , wherein said accelerator is an accelerator which emits the particle beam with a pulse width shorter than the wobbler cycle, and wherein said irradiation controller alters the number of pulses of the particle beam every layer of the stacked conformation radiotherapy, thereby controlling the irradiation dose of each layer and performs a control so that an integral multiple of an emission cycle of the pulses of the particle beam is an integral multiple of the wobbler cycle. 
     
     
       4. A stacked conformation radiotherapy system as defined in  claim 1 , wherein in addition to the control of the irradiation dose of each layer in the depth direction of the object to-be-irradiated, said irradiation controller alters irradiation energy of the particle beam every layer, thereby to perform a control so that the dose distribution in the depth direction of the object to-be-irradiated is flat. 
     
     
       5. A stacked conformation radiotherapy system as defined in  claim 1 , wherein the one-stroke revolving orbit is a circular orbit or a zigzag orbit. 
     
     
       6. A particle beam therapy apparatus comprising the stacked conformation radiotherapy system as defined in  claim 1 .